It suggests "moderate-severe" activity in most southeastern, south central, and central states, as well as in Alaska and Hawaii.

Google Flu Trends, based on Internet searchers for flu-related topics, shows high national flu activity. The greatest flu activity, according to Google Flu Trends, is currently in:

Alaska

Georgia

Louisiana

Mississippi

Tennessee

The Flu Near You map, based on weekly self-reported flu symptoms, shows high activity throughout the South.

"It is just a matter of time where we will have high flu activity across the nation," says Melinda Wharton, MD, acting director of CDC's National Center for Immunization and Respiratory Diseases.

Flu Vaccine Supply

Vaccination remains the best way to avoid the flu. So far this year, the CDC estimates that 112 million Americans already got their flu shots (or sniffs of the nose-spray vaccine). That would be about 37% of the vaccine-eligible U.S. population over age 6 months.

Manufacturers have shipped 123 million of this year's expected 135 million doses of flu vaccine.

So far, the CDC says nobody who wants flu vaccine is having trouble finding it.

"We are similar in vaccine [supply and demand] to last year," Frieden said. "We did not have a shortage last year, and expect no shortage this year."